Lewistown Weather in September

What's the weather like in Lewistown (Montana) in September 2025?

The climate in Lewistown during September can be summarized as mild and reasonably dry.

September is in the fall / autumn in Lewistown and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a cool 20°C (69°F), whilst at night 5°C (40°F) is normal.

Lewistown weather averages (imperial / metric)
Daytime temperature 20.3°C 68.5°F
Nightly temperature 4.5°C 40.1°F
Average temperature 12.4°C 54.3°F
Daily sunshine 9.3 hrs
Avg rainfall 37 mm 1.5 ins
Rainy days 7 days
Sea temperature 13.5°C 56.3°F
Humidity 53%
Windspeed 17.3kph 11 mph

On average September is the 5th wettest month of the year in Lewistown with around 37mm 1.5 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 7 days, although this may vary considerably.

On the flip side this corresponds to an average of 9.3 hours of sunshine per day.

September temperatures in Lewistown

Lewistown average temperature in September

September rainfall

Lewistown average rain in September

September hourly sunshine

Lewistown average rain in September

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Lewistown in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Lewistown weather stats

Lewistown weather statistics
Hottest month: July 27°C 80.6°F
Driest month: February 16mm 0.6ins
Sunniest month: July 13hrs
Coldest month: January -1.4°C 29.5°F
Wettest month: May 82mm 3.2ins
Map showing location of Lewistown (47.06247, -109.42824) Lewistown map pin © Google

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